Novel method for installing and fixing plastic wind wheel

Abstract

The invention relates to a novel method for mounting and fixing a plastic wind wheel of a household appliance, which is characterized in that the industry pass method of using a rubber / latex flat gasket (adhered to the side of a plastic hub and buffering extrusion of a nut), adding a lock washer / spring washer and finally screwing a locking nut is abandoned, and the plastic wind wheel is fixed on a motor shaft by using a plastic material; according to the novel method, the plastic wind wheel shaft sleeve can be effectively prevented from being cracked due to the fact that the locking nut is screwed too tightly, the locking nut can be prevented from being loosened due to the fact that the locking nut is screwed too loosely, and the plastic wind wheel rotating at a high speed moves in the axial direction and is scratched with a shell to be damaged. And the coefficient of cold shrinkage and thermal expansion is consistent or close, so that the problem of stress cracking of the plastic wind wheel caused by temperature change is also solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a new method for installing and fixing a plastic wind wheel of a household appliance, which abandons the industry common practice of using rubber / latex flat pads (pasted on the plastic hub side, buffer nut extrusion), adding lock washer / spring washer, and finally tightening the lock nut, and instead uses plastic material to fix the plastic wind wheel on the motor shaft without increasing product cost, and the operation method is simple and easy to master, and the quality is stable and reliable. BACKGROUND

[0002] There are mainly three methods for installing and fixing a plastic wind wheel of a household appliance: 1. the most commonly used method is "shaft end nut locking + anti-loose"; 2. small centrifugal wind wheels use "top screw (set screw) fixing + shaft surface knurling"; and 3. micro wind wheel toy fans use the simple method of "shaft sleeve + clasp spring (buckle) fixing".

[0003] The present application is a solution to the congenital defects of the most commonly used "shaft end nut locking + anti-loose" method.

[0004] To effectively fix a high-speed rotating wind wheel, the first problem encountered is to prevent the lock nut from loosening, and to prevent the high-speed rotating plastic wind wheel from axially moving and scratching the shell, which leads to damage, and the industry generally adds a lock washer and a spring washer under the lock nut, and then tightens the nut, relying on friction to prevent the lock nut from loosening.

[0005] The generation of friction must meet three conditions at the same time:

[0006] Two objects are in contact and are extruded to generate pressure;

[0007] The contact surface is rough;

[0008] There is relative motion or a tendency for relative motion between the two objects.

[0009] Therefore, pressure is the premise for the generation of friction - without pressure, even if the contact surface is rough and there is a tendency for relative motion, no friction will be generated.

[0010] For sliding friction (friction between objects when relative sliding occurs), the relationship formula between the size of the sliding friction and the pressure is: f=μN

[0011] Wherein:

[0012] f is the sliding friction

[0013] μ is the dynamic friction factor

[0014] N is the normal pressure between the contact surfaces

[0015] Under the condition that the contact surface does not change (μ does not change), the sliding friction is proportional to the pressure.

[0016] If the pressure is 0, the sliding friction is also 0.

[0017] According to the above formula, the sliding friction f is proportional to the normal pressure N between the contact surfaces, which means that the tighter the lock nut is tightened, the greater the normal pressure N between the contact surfaces, the greater the sliding friction f, and the better the anti-loose effect.

[0018] But the nut is too tight will cause another extreme problem: the plastic wind wheel due to excessive extrusion of external force stress cracking damage. Production line to prevent the lock nut forceful tightening, using rubber pad / latex pad instead of stainless steel washer, to buffer and disperse the extrusion force of the nut, and then set the lock washer / spring washer, finally also need to restrain the production line workers with wrench to tighten the nut force, but only with "don't over tighten", "don't forceful tightening" and other concepts that even technical staff can not be quantified, let the workers on the assembly line to grasp the tightening force of the lock nut is not operational.

[0019] From the fastener structure, the motor shaft limit pin is located at the lower end of the motor shaft, which is a cylindrical steel material, fixed by interference fit. The plastic wind wheel is sleeved on the motor shaft and vertically placed on the motor shaft limit pin. The motor shaft limit pin holds up the plastic wind wheel to realize axial positioning and anti-loose. In combination with the fastening nut, washer and other components at the top of the plastic wind wheel shaft, the plastic wind wheel is locked and fixed on the motor shaft to prevent axial movement or falling during rotation.

[0020] As mentioned above, the main way to prevent the lock nut from loosening is to increase the tightening force of the lock nut. Rubber / latex pad can disperse and buffer the extrusion force of the nut, but the pressure will not disappear. The pressure of the lock nut is transmitted to the motor shaft limit pin through the plastic wind wheel shaft. The plastic wind wheel shaft and the motor shaft limit pin are in hard contact, and there is no soft pad to buffer between them. The plastic wind wheel is locally stressed and generates internal stress. If the internal stress exceeds the allowable elastic deformation limit of plastic, it will crack after a short period of static state. Especially after a large temperature change in severe cold / hot weather, the stress cracking risk will be increased due to the large difference in shrinkage coefficient and expansion coefficient between metal and plastic. Professional and technical personnel in the industry have no solution to this problem. Therefore, we can see that high-priced products with technical barriers and brand premium will abandon plastic wind wheels and use metal wind wheels with much higher cost, or embed metal shaft sleeves in the plastic wind wheel shaft core during injection molding to resist the pressure brought by the lock nut. High failure rate, high return rate and high after-sales repair rate caused by plastic wind wheel cracking are the curse that small household appliance industry cannot escape. For small household appliance industry with mature technology and no technical threshold, any increase in the cost of accessories will not only infringe the already meager profit, but also weaken the market competitive advantage. SUMMARY

[0021] The purpose of the present application is to provide a new method for installing and fixing a plastic wind wheel, abandoning the industry common practice of using locking nuts to fasten the wind wheel, and instead using plastic material to fix the plastic wind wheel on the motor shaft. This new method can eliminate the uncontrollable external pressure on the plastic wind wheel caused by the locking nuts, thereby avoiding stress cracking of the plastic wind wheel shaft caused by external pressure.

[0022] To achieve the above-mentioned purpose of the application, the applicant provides the following technical solutions.

[0023] The new method for installing and fixing the plastic wind wheel has an outer threaded motor shaft, and the plastic wind wheel is inserted into the shaft end with exposed threads. After filling and sealing the top end of the plastic wind wheel shaft hole with hot melt glue between the exposed threads of the motor shaft, the plastic wind wheel is locked and fixed on the motor shaft. Hot melt glue is a common filling and bonding glue stick on the production line. After inserting the hot melt glue stick into the hot melt glue gun and heating and melting it, the wind wheel is rotated to press the hot melt glue around the top end of the plastic wind wheel shaft hole and the exposed threads of the motor shaft. The hot melt glue will quickly cool and solidify. During after-sales maintenance, the solidified hot melt glue can be cut off with a water mouth tongs and pulled out as a whole.

[0024] The new method for installing and fixing the plastic wind wheel has an outer threaded motor shaft, and the plastic wind wheel is inserted into the shaft end with exposed threads. After filling and sealing the top end of the plastic wind wheel shaft hole with hot melt glue between the exposed threads of the motor shaft, the plastic wind wheel is locked and fixed on the motor shaft. Hot melt glue is a common filling and bonding glue stick on the production line. After inserting the hot melt glue stick into the hot melt glue gun and heating and melting it, the wind wheel is rotated to press the hot melt glue around the top end of the plastic wind wheel shaft hole and the exposed threads of the motor shaft. The hot melt glue will quickly cool and solidify. During after-sales maintenance, the solidified hot melt glue can be cut off with a water mouth tongs and pulled out as a whole.

[0025] The new method for installing and fixing the plastic wind wheel has an outer threaded motor shaft, and the plastic wind wheel is inserted into the shaft end with exposed threads. After filling and sealing the top end of the plastic wind wheel shaft hole with hot melt glue between the exposed threads of the motor shaft, the plastic wind wheel is locked and fixed on the motor shaft. Hot melt glue is a common filling and bonding glue stick on the production line. After inserting the hot melt glue stick into the hot melt glue gun and heating and melting it, the wind wheel is rotated to press the hot melt glue around the top end of the plastic wind wheel shaft hole and the exposed threads of the motor shaft. The hot melt glue will quickly cool and solidify. During after-sales maintenance, the solidified hot melt glue can be cut off with a water mouth tongs and pulled out as a whole.

[0026] The beneficial effects of the technical solution of this invention are as follows: the new method does not rely on extrusion force to fasten the plastic impeller, thus technically eliminating stress cracking of the plastic impeller caused by external force. It uses conventional materials found on production lines, without increasing product costs. The operation method is simple and easy to master, and the quality is reliable and stable. It completely eliminates the influence of human factors such as damage to the plastic impeller caused by violent tightening or excessive loosening of the locking nut in traditional methods. This significantly reduces the defect rate and return rate caused by cracking of the plastic impeller, and greatly reduces after-sales maintenance costs. The material used in the new method is the same or similar plastic material as the plastic impeller, with the same or similar coefficients of shrinkage when cold and expansion when hot. Therefore, it will not cause stress cracking of the plastic impeller due to external pressure caused by temperature changes.

Claims

1. A novel method for installing and fixing a plastic impeller, wherein the motor shaft has external threads, and the plastic impeller is fitted onto the rear shaft end with exposed threads, characterized in that... Plastic material is used to lock and fix the wind turbine to the motor shaft between the top of the plastic wind turbine shaft hole and the exposed thread of the motor shaft, instead of the metal nut commonly used in the industry.

2. The novel method for installing and fixing a plastic wind turbine according to claim 1, characterized in that: After hot melt adhesive is used to fill and seal the gap between the top of the plastic impeller shaft hole and the exposed thread of the motor shaft and the solidified layer, the plastic impeller is locked and fixed onto the motor shaft.

3. The novel method for installing and fixing a plastic wind turbine according to claim 1, characterized in that... At least two latex flat washers with a hole diameter smaller than the diameter of the motor shaft and a thickness of not less than 3 mm are used to press and fix the plastic impeller to the motor shaft between the top of the plastic impeller shaft hole and the exposed thread of the motor shaft.

4. The novel method for installing and fixing a plastic wind turbine according to claim 1, characterized in that: Use a plastic bushing to fit the exposed threaded part of the motor shaft at the top of the plastic impeller shaft hole. Use a hot melt machine to heat and soften the plastic bushing, then apply pressure and cool to shape it. Lock and fix the plastic impeller to the motor shaft.